Question answering (QA) is a field in computer technology that attempts to automatically provide answers to questions input by humans, often in natural language format. For example, in response to the input question, “What is the capital of Liechtenstein?” a QA system would be tasked with determining and outputting the answer that the capital of Liechtenstein is Vaduz.
While some QA systems may perform searches on text documents, such as web pages, as part of the process of identifying answers to questions, QA systems differ from document search and retrieval systems such as typical Internet search engines. The latter systems typically perform keyword searches to retrieve documents (e.g., web pages) that contain keywords from the search query. For example, if “What is the capital of Liechtenstein?” were input as a search query to a conventional Internet search engine, the output would typically be a list of one or more web pages whose texts contain the keywords “capital” and “Liechtenstein.” The user might then be able to examine each returned document to see if it contains the answer that the user was looking for (i.e., that the capital city is Vaduz).